1. Field of the Invention
The present invention relates to an information processing device which operates according to a program, and a program execution control method employed by the same.
2. Description of the Related Art
In recent years, problems have emerged with information processing devices, including one in which a party without valid authority executes a program subjected to falsification to cause information to be disseminated contrary to the user's intention.
Some information processing devices may aim to execute only a program having a valid license granted, and even among those programs having valid licenses granted, there are some programs which ought to be prevented from being executed by an information processing device other than a legitimate information processing device while utilizing software such as an emulator, or the like.
For these purposes, some conventional methods are available, such as is disclosed in U.S. Pat. No. 5,937,063, or the like, including one in which a program is encoded in advance and decoded later on the processor side for execution.
Another method may be such that a hash value issued in advance for each program is stored at the time of activation of the program, so that a processor serving as a program execution module authenticates a program to be executed while referring to the stored hash value.
However, according to the above-described conventional method, as the entity for program execution and that for decoding and verification are the same, a situation cannot be handled in which the program for decoding and verification is exchanged with an illegal one. Also, according to the method using a stored hash value, a problem remains unsolved as to how to securely hold a hash value of a program to be developed after production of the product.